Gas concentration sensors, such as NOx sensors, may be used in many different settings. For example, these sensors may be used in vehicles for monitoring concentrations of species in engine exhaust. As further improvement of combustion control is desired and emission regulations become more restrictive, the accuracy of these sensors becomes increasingly important. Unfortunately, the accuracy of these sensors may decrease with sensor aging due to a drift in the baseline output of the sensor.
One approach for obtaining an updated value for the baseline output is to measure the sensor output when there is known to be an absence of NOx in the exhaust gas. However, there may be an uncertainty regarding whether the analytical gas sample is sufficiently free of NOx when updating the baseline.
In one approach, the above issues may be addressed by a method of operating a gas sensor including a pumping electrode configuration and a measuring electrode configuration, the method comprising operating the sensor in a first mode in which a first, lower pumping potential sufficient to electrochemically remove an interfering compound from the sensor without electrochemically removing the analyte from the sensor is applied across the pumping electrode configuration and a measuring potential sufficient to electrochemically remove the analyte from the sensor is applied across the measuring electrode configuration, and operating the sensor in a second mode in which a second, higher pumping potential sufficient to electrochemically remove the analyte from the sensor is applied to the pumping electrode configuration. In some embodiments, a baseline output of the sensor may be determined while operating the sensor in the second mode.